In recent years, research and development are in progress of large-sized organic EL display panels using organic EL elements. In a typical organic EL display panel, a plurality of organic EL elements are arranged in a matrix along a main surface of a substrate serving as a support member, and an image is displayed on an image display face by the organic EL elements forming pixels.
In an organic EL element, one or more functional layers, including at least a light-emitting layer containing an organic compound, are sandwiched between a pair of electrodes. The functional layer may also include layers other than the light-emitting layer, such as an injection layer, a transport layer, a blocking layer, and a buffer layer. Formation methods for functional layers are broadly categorized into dry processes such as vacuum vapor deposition, and wet processes such as inkjet application. Wet processes involve use of a solution (hereinafter termed “ink”) containing functional layer material (functional material), and are considered to be suitable for the enlargement of display panels in terms of formation precision and cost. Particularly, development is in progress of inkjet application, which is a method where ink in the form of fine droplets is discharged to be directly applied to pixel formation regions on a substrate.
Ink application involves discharging ink to pixel formation regions on a substrate from a plurality of nozzles lining up in a straight line, while displacing the nozzles relative to the substrate in a predetermined scanning direction along a main surface of the substrate. Typically, the scanning direction is set to be parallel to either a row direction or a column direction of a matrix made up of the pixel formation regions. In addition, a technology is disclosed of adjusting the distance between application positions corresponding to adjacent nozzles by inclining the nozzle array direction relative to the scanning direction (see, for example, Patent Document 1).